Being able to flexibly and effectively utilize emotion regulation strategies is essential to health and well-being. Persistent failure to do so is associated with deficits in many aspects of well-being and is a hallmark of many forms of psychopathology. This is particularly true of borderline personality disorder (BPD), an enduring mental illness involving significant suicidality and in which emotion dysregulation and affective instability are cardinal features. One critical but understudied question in the emotion regulation literature is whether individuals (with and without psychopathology) can improve in their ability t apply a potentially impactful and adaptive cognitive regulation strategy, cognitive reappraisal, over time through relatively brief courses of focused training. Reappraisal is a cognitive change emotion regulation strategy that involves re-framing an affective stimulus in a way that alters its emotional impact. Though several cognitive-behavioral therapies currently used in clinical practice to treat BPD (including dialectical behavioral therapy; DBT) employ reappraisal along with other techniques, the trainability of reappraisal in particular has only just begun to be examined. Using methods from social cognitive neuroscience as well as translational clinical science, the present research examines whether a short, intensive course of training in one particularly promising form of reappraisal-psychological distancing-can improve emotion regulation efficacy in three relevant populations: BPD patients; patients diagnosed with a near-neighbor personality disorder also involving emotion dysregulation, avoidant personality disorder (AvPD); as well as healthy adult controls (HC). Three specific aims will be addressed. Aim 1 will examine whether a relatively short, 6-session course of distancing training using an image-based task will reduce self-reported negative affect in BPD patients, AvPD patients, and HC's. Aim 2 will use functional magnetic resonance imaging (fMRI) to examine the neural mechanisms supporting distancing training using this task (measured at three of the six training sessions) both within and across sessions, with an a priori focus on longitudinal changes in the activity of the amygdala and other appraisal-related brain areas, including the insula. In so doing, both Aims 1 and 2 will examine novel questions concerning the ability of psychopathologically relevant dimensional constructs (emotion dysregulation, negative affectivity, and affective instability) to predict task-based behavioral and neural responses transdiagnostically (i.e. across BPD's, AvPD's, and HC's). Critically, Aim 3 will further examine whether the results of Aims 1 and 2 (behavioral and fMRI data during training, respectively) predict long-term clinical outcomes in BPD patients who complete a course of skills training DBT. The present approach has potential translational significance in providing insight into the mechanisms underlying emotion dysregulation and regulation improvement across populations as well as predicting which BPD patients are most likely to benefit from therapy.